Combing elements of this general type are combined in the form of needle bars or bars of stamped sawtooth elements and are installed in spinning machines for the purpose of removing impurities contained in wool or cotton fibers and to align the fibers so that they are generally parallel. The pieces of straw or burls combed out of the wool or cotton are deposited at the combing elements. In addition, short pieces of fiber and other impurities may be deposited in the gaps between the combing elements and in this way considerably hamper their combing action. It is known to provide cleaning blades for cleaning top combs constructed from needle bars, which clean the top combs subsequent to the combing cycle. Furthermore, the use of cleaning brushes is known in connection with wool combing machines. These already known cleaning means can only be used to a limited extent in connection with top combs and cannot be used at all in connection with other combing devices, such as rotating combing units.
A completely novel way for cleaning needle bars, in particular of top combs, has been disclosed in U.S. Pat. No. 4,928,356 where in accordance with the exemplary embodiments described therein compressed air is supplied via an air chamber, laterally arranged on the needle bars, which enters the combing tip area of the needles below the lower edge of the cover plates of the needle bars and cleans it of impurities and short fibers deposited there. This concept of compressed air cleaning has proven to be excellent and has resulted in a considerable improvement of the combing quality.